1. Field of the Invention
The present invention is in the field of activation closures for vials. More particularly, the present invention is directed to an activation closure cap for a two-compartment vial which has improved control over the stopper, permits removal of the closure cap and subsequent recapping of the vial without significant risk of contamination of the contents, of the environment and the user, and which optionally also allows access to contents of the vial by piercing the closure with a hypodermic needle.
2. Brief Description of the Prior Art
Two-compartment vials have been known in the art for a long time and are presently in widespread use. The two compartments of such vials are typically separated by a neck portion which has an internal stopper or plug. The plug forms an efficient liquid seal between the two compartments. Each compartment contains a substance which, for some reason, should not be brought into contact with the substance in the other compartment before use, that is, while the vial and its contents are in transit and storage. A closure cap (or simply closure) seals the upper compartment of the two-compartment vial. However, in order to permit contact between the two substances in the two separate compartments of the vial when such contact becomes desirable, the closure cap provides means for dislodging the internal stopper or plug from the intermediate neck portion of the vial, and thereby allows the substances in the two compartments to mix. The upper compartment contains a liquid, and the closure cap includes a rubber stopper which, when pressed in a downwardly direction creates sufficient hydrostatic pressure on the liquid to dislodge the internal stopper, cause it to fall into the lower compartment and thereby remove the internal stopper from between the two compartments.
The above-summarized two-compartment vials are widely used in connection with medication of the type wherein two (or more) components need to be mixed just before administration to a patient. Typically in such application the lower compartment contains a lyophilized powder (of an antibiotic, for example) and the upper compartment contains a diluent solution in which the lyophilized powder is to be dissolved before injection to a patient. Such medication, of course, needs to be sterile. Therefore, after mixing or "reconstituting" the sterile medication, it is withdrawn from the vial by piercing the rubber stopper of the closure member with a hypodermic needle attached to a syringe. The closure member or cap for such a vial is sometimes called an "activation closure", because the step of dislodging the internal stopper or plug (thereby allowing the components of the two compartments to mix) activates the contents. U.S. Pat. No. 4,331,233 describes a two-compartment vial with an activation closure which greatly reduces the possibility of inadvertently pushing the rubber stopper of the closure too far into the compartments. The closure cap of this reference patent also permits efficient withdrawal of the contents of the vial with a hypodermic syringe and needle.
Vials are also used in diagnostic and like medical laboratory applications, where the "activated" contents of the vial do not comprise medications (such as parenterial injections for humans or animals) but rather where the contents are utilized as a reagent or "standard" in diagnostic and like tests. For example, all licensed medical laboratories in the United States of America are required to use certain control serums in connection with laboratory tests of human blood serum. Typically, the solid lyophilized control serum is provided in accordance with the art in a single compartment vial equipped with a pierceable stopper or closure member, to which purified water (or other suitable diluent) is added before use. A disadvantage of the latter single compartment vial is that it introduces the possibility of human error with regards to the identity, quantity and quality of the diluent which is added to the lyophilized control serum.
In such diagnostic or laboratory application however, it is usually desirable to extract only an aliquot portion of the sample solution (standard or control serum) which is formed after activation. Typically, the sample solution (standard or control serum) is stored for a long time in refrigerated condition, and further aliquot portions are withdrawn from time-to-time until the solution is used up. The aliquot portions or samples can be withdrawn with a hypodermic needle and syringe by piercing a rubber stopper in the closure member. However, because of the inherent danger from needle sticks, laboratory personnel typically prefer to remove the closure member altogether, and extract a sample from the temporarily uncapped vial with a pipette (or the like). Both of these procedures in accordance with the above-summarized prior art have their disadvantages. Removal of the closure cap of a vacuum packed lyophilized vial before a diluent is added raises the possibility of aerosol formation and the use of hypodermic syringe and needle raises the possibility of accidental pricking of laboratory personnel, which in view of acquired immunodeficiency syndrome and other diseases transmitted through blood or serum, is to be strictly avoided. Removing the closure member from the neck of the vial in order to permit withdrawal of a portion with a pipette (or the like) raises the danger of contaminating both the sample, the work environment and the laboratory worker. This is because the closure member must be typically placed on a support surface such as a laboratory table, where the rubber stopper actually touches the surface with the possibility of leaving traces of the vial's contents behind, and also with the possibility of the stopper picking up impurities from the support surface and introducing it into the sample.
In addition to the foregoing operational problems, the art pertaining to closure members for two-compartment vials and the like, is also burdened with problems of more technical nature, such as the fact that glass vials cannot be mass produced inexpensively with very tight tolerances, the need for perfect or nearly perfect liquid internal seals for the vials, the need for avoiding inadvertently pushing the rubber stopper too far into the upper compartment when the contents of the two-compartment vial are activated, and the need for avoiding, as much as possible, frangible metal members which may have sharp edges capable of inflicting injury to laboratory personnel.
U.S. Pat. Nos. 4,089,432, 4,180,173, 4,267,925, 4,274,543, and 4,194,640 describe various closure structures of the prior art which attempt to solve one or more of the above noted problems. Nevertheless, there is still a need in the art for improvements in two-compartment vial closures, especially for laboratory and diagnostic applications. The present invention fills this need.